Jeezy, I hate to burst your bubble, but, it doesn't look THAT bad. Maybe it's worse in real life, or I'm just a "glass half full" kind of guy, but, it doesn't look that bad.
It looks like your masking went over pretty well, but probably just applied the paint on a little thick is all. But the shapes and placement of the weathering look good. The hours you spent doing that definitely paid off.
I think the only advice I can give is lighter coats of paint. Applying with an airbrush might help out with that a bit too.
Don't beat yourself up too much man. That looks a helluva lot better than my first two painting attempts did! 
Jer